Allow the pre-150 built-in redeclarations when using SSO: gl_Position, gl_PointSize, gl_ClipVertex, and gl_FogFragCoord.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@26399 e7fa87d3-cd2b-0410-9028-fcbf551c1848

Test/140.vert

@@ -19,3 +19,15 @@ void main()
     gl_FogFragCoord;    // could be ERROR, but compiling under compatibility profile
     gl_FrontColor;      // could be ERROR, but compiling under compatibility profile
 }
+
+out vec4 gl_Position;  // ERROR
+
+#extension GL_ARB_separate_shader_objects : enable
+
+out vec4 gl_Position;
+in vec4 gl_Position;   // ERROR
+out vec3 gl_Position;  // ERROR
+
+out float gl_PointSize;
+out vec4 gl_ClipVertex;
+out float gl_FogFragCoord;